Math类和字符串连接符"+"

幂运算

Math类

public class Demo04 {
    public static void main(String[] args) {

    //幂运算 2^3 2*2*2 = 8
    double pow = Math.pow(2,3);
    System.out.println(pow);
    }
}

字符串连接符 +，String

两者区别

public class Demo07 {
    public static void main(String[] args) {
        int a = 10;
        int b = 20;

        System.out.println(""+a+b);
        //1020
        
        System.out.println(a+b+"");
        //30
    }
}